The present invention relates to a rechargeable battery pack attachable to a power tool.
Conventionally, this kind of rechargeable battery pack is known in which a plurality of display elements are arranged on an outer wall thereof and which is configured to display a remaining capacity of a rechargeable battery by controlling the number or the like of lighted display elements (see Japanese Unexamined Patent Application Publications Nos. H07-161340, 2004-312789, for example).
Further known are a power tool to which this kind of rechargeable battery pack is attached and a battery charger that charges the rechargeable battery pack. The power tool and the battery charger are configured to determine whether or not an output voltage from the rechargeable battery, an electric current flowing through the rechargeable battery and the like are normal and to display results of the determinations (see Japanese Unexamined Patent Application Publications Nos. 2002-210678, H07-282858, for example).